Blue Bottle Reaction

Materials

Solution A: 8gm KOH in 300ml H2O

Solution B: 10gm glucose

Solution C: 1% methylene blue solution

500 mL Wide Mouthed Bottle with Cap

Gloves and Goggles

       

Procedure

  • Just before class starts, add glucose and 4 drops methylene blue solution to the KOH solution in the 500 mL bottle and mix until clear.
  • Show the class the stoppered flask containing the solution.
  • Give the flask a few shakes. The solution will turn blue.
  • After a few seconds, solution becomes clear.
  • This process can be repeated several times. The bottle may have to be unstoppered to introduce O2.

       

Reactions

O2 (g) --> O2 (dissolved)

    

O2 (dissolved) + methylene blue --> methylene blue 
                             (colorless)                  (blue)

glucose + OH- --> glucoside

glucoside + methylene blue --> methylene blue + OH-
                        (blue)                   (colorless)

       

Waste Management

The used solutions from this demonstration can be neutralized and then poured down the sink.

Lecture Demonstrations